Draw-bridge



' 2 Sheets-Sheet 1.

(No Model.)

W. J. BRIGGS.

DRAW BRIDGE.

naw/who; m J. B2 9 3 Patented Aug. 14, 1888.

. uu/ mm (No Model;)

2 SheetsSheet 2.

W. J. BRIGGS.

DRAW BRIDGE.

Patented Aug. 14, 1888.

N. PETERS. wbuzm u m, Washington. a. c

IINrrEn TATES PATENT FFIQEQ \VILLIAIII J. BRIGGS, OF SOUTH EVANSTON,ILLINOIS.

DRAW-BRIDGE.

SPECIFICATION forming part of Letters Patent No. 387,852, dated August14, 1888.

Application filed November 8, 1887. Serial No. 254,645. (No model.)

To aZZ 211710721, it may concern:

3e it known that 1, WILLIAM J. BRIGGS, a citizen of the United States,residing at South Evanston, in the county of Cool: and State ofIllinois, have invented a new and useful Improvement in Draw-Bridges, ofwhich the following is a specification.

My invention relates to improvements in drawbridgcs; and it consists incertain novel features, hereinafter described and claimed.

In the accompanying drawings, which fully illustrate my invention,Figure 1 is a longitudinal vertical section of a draw-bridge embodyingmy improvements, and Fig. 2 is a horizontal section on linear cc ofFig. 1. Fig. 3 is an end elevation of the draw, and Fig. 4

an elevation of the gate.

Referring to the drawings by letter, A desi gnates the draw, and B aportion of the bridge. The end of the draw is formed in the arc ofacircle, and the end of the bridgesection is cut away on a similar are,so that the draw may swing freely past the same, as will be readilyunderstood on reference to Fig. 2. At the end of the bridge-section, onopposite sides there of, I erect the posts or columns 0 O, and on theinner opposing sides of these columns I secure the track-irons E,whichare doubled on themselves longitudinally at their centers, so as to formthe grooves or ways F and the lateral flanges G, which are secured tothe posts.

II designates the gate, which is provided at its ends with theguide-plates 1', having a longitudinal rib, J, which engages the grooveF, and thereby guides and steadies the gate in its movements.

8 T designate hollow columns which are erected between the sidewalks andthe carriage-road of the bridge, and have pulleys D journaled in theirupper ends.

The gate is supported by cables K, which are secured to its top rail onopposite sides of the center thereof and pass over the pulleys D,counterbalancirig-weights L being secured to the cables within thecolumns S T. Near the lower edge of the gate, and midway the ends of thesame, I provide the forwardly-projecting pin M, on which I mount afriction-roller, N. The lower portion of the end of the draw is cutaway, as shown at 0, so as to provide the shoulder P. This shoulderinclines down wardly from each side of the draw to the center and actsas a cam upon the pin M to force the gate downward and hold it in itslowered position. This cam-shoulder I has a wearstrip, Q, secured to itsunder face, so as to preserve its surface, and at its lowest centralpoint it has a short horizontal portion, R.

The construction of my device being thus understood, its operation andadvantages will be readily apparent.

IVhen the draw is closed, as shown in Fig. 1, the horizontal portion Itof the cam-shoulder thereof will be resting upon the pin M on the gate,thereby holding the gate in its lowered position. If the draw be swungto either side in order to open the same, the weight L will raise thegate and hold the pin M against the cam shoulder of the draw, andconsequently cause the same to ride up the inclined portions of the saidshoulders, as will be readily understood. The draw when swung back willcause its cam-shoulder to impinge upon the pin on the gate, and therebylower the gate. The roller N reduces the friction between the contactingparts and renders the operation of the device smooth, easy, and certain.

It will be seen that my device is simple in construction, and theeiiicieucy of its operation is thought to he obviously apparent. Thegate is caused to move in a true vertical plane by the track-irons andguide-plates heretofore mentioned, and is prevented from rising to toogreat a height by a stop or guardflV, projecting laterally from theinner side of the columns near their upper ends.

I am aware that heretofore draws for bridges have been provided with aprojecting camstrip which operated the gate by acting on a pin or rolleron the same. This construction left an open uprotected space between theends of the draw and the bridge-section equal to the width of thecam-strip. These openings are dangerous, for the reason that passengersover the bridge are liable to fall into the same and be injured.

By my construction the strength of the draw and the bridge isunimpaired, and I am enabled to bring the several parts in such closerelation that a practically unbroken surfacci. s formed by the top ofthe gate and the opposing ends of the draw and the gate-section. I thusobviate the danger of passengers being injured by being caught in theopen crevices, as above referred to.

Having thus described my invention, what I claim, and desire to secureby Letters Patent, 1s-

1. The combination of the posts, the trackirons secured thereto, thegate having a forwardly projecting pin at its center near its loweredge, the guide plates secured to the gate and moving on thetrack-irons, and the draw havingitslower portion cut away to provide acam-shoulder adapted to contact with the pin at the lower portion of thegate to 0p erate the same, substantially as specified.

2. The combination of the posts, the trackirons secured thereto having alongitudinal groove, the gate, and the guide-plates secured thereto andhaving a longitudinal rib engaging the groove in the track-iron,substantially as described.

3. The combination of the gate having guideplates on its ends, the postserected at the ends of the gate and having track irons engaged by theguide-plates thereon, the posts erected at intermediate points of thelength of the gate and having pulleys in their upper ends, and theweighted cables secured to the top rail of the gate and passing oversaid pulleys, substantially as specified.

In testimony thatI claim the foregoing as my own I have hereto afiixedmy signaturein pres ence of two witnesses.

WILLIAM J. BRIGGS.

Witnesses:

G130. M. STEVENS, CLAYTON E. (Dreams.

